1. Field of the Invention
The present invention relates to a modified zeolite catalyst useful for the conversion of paraffins, olefins and aromatics in a mixed feedstock into isoparaffins. More particularly, the present invention relates to a porosity and acidity modified zeolite comprising one or two noble metals. The present invention also relates to a process for the conversion of paraffins, olefins and aromatics in a mixed feedstock into isoparaffins. The utility of the process is for upgrading the octane number of a industrial feedstock such as desulfurized FCC gasoline through conversion of most of the olefins and aromatics present in it into environment friendly branched paraffins, using porosity improved, noble metal containing zeolite based catalyst, so as to meet the quality requirement of fuel to use as gasoline blending stock.
2. Description of Related Art
Environmental concern and restriction on fuel quality especially on the restriction on the amount of sulfur, aromatic and olefins in FCC gasoline demands novel catalyst and process for hydrocarbon conversion. The octane loss occurred during traditional sulfur removal process also demands hydrocarbon conversion process for octane boosting in an eco-friendly way. The present invention relates to a process for hydroconversion of feedstocks, especially FCC gasoline, to a catalyst for use in hydro conversion process with a feedstock having high amount of paraffins, olefins and aromatics to produce branched paraffin and to a process provides such catalyst.
Reference may be made to the U.S. Pat. No. 4,734,539 to Lawlor et al, wherein a process for the isomerization of paraffins is disclosed. The drawback of the process is that the catalyst has one dimensional pore system that leads to rapid deactivation by coke as well.
References may be made to U.S. Pat. No. 4,962,269 to La pierre et al, wherein a process for isomerization of paraffins using zeolite catalyst was described. The drawback of the process is the formation of considerable amount of aromatics that are undesirable for the production of green gasoline. On the other hand, the present invention deals with the conversion of aromatics into iso-paraffins.
Reference may be made to U.S. Pat. No. 5,770,047 to Salazal et al, wherein a process for removal of sulfur and nitrogen from the heavy naphtha was described. The process also describes a GaCr/ZSM-5 catalyst for the isomerization of paraffin. The drawback of the process is the formation of considerable amount of undesirable gases (C1-C4 up to 25%).
Reference may be made to the U.S. Pat. No. 5,057,472, wherein a process for dealumination of zeolites, especially by adding ammonium nitrate and nitric acid for obtaining effective isomerization catalyst that can isomerizes n-paraffins to isoparaffins. However, the process does not cover the procedure for obtaining the zeolite with improved surface area, porosity or acidity and improved Pt dispersion that are essential for conversion aromatics, olefins and naphthenes into isoparaffins. The patent also does not mention its effectiveness for conversion of aromatics viz. especially for the conversion of benzene so as to meet the requirement of gasoline specifications.
Reference may be made to the U.S. Pat. Nos. 5,238,677 and 4,485,005, wherein processes for dealumination of mordenite using an acid such as dicarboxylic acid and steaming have been described. The catalysts are tested for their alpha activity related to its cracking ability and for the cracking of long chain vacuum gas oil. However, the processes do not discuss the improvement in catalytic properties such as porosity and acidity, and its catalytic activity towards the conversion of olefins, naphthenes and aromatics.
Reference may be made to the U.S. Pat. No. 6,964,935, wherein the patent describes a process for alkylation of benzene with long chain olefins to produce alkyl aromatics. The process does not cover the conversion of short chain paraffins, olefins, naphthenes and aromatics into gasoline range isoparaffins. Nitric acid was used for peptization of extrudates but not for dealumination purpose.
Reference may be made to the U.S. Pat. No. 3,507,931 (MORRIS), U.S. Pat. No. 4,018,711 (BERTOLACINI), U.S. Pat. No. 4,400,576 (SHELL), U.S. Pat. No. 3,480,539 (ESSO), wherein a process for the isomerization of paraffins was described using a zeolite treated with steam and acids at severe conditions prior to the contact with feed. But, the processes limits to the conversion of paraffins into isoparaffins. Whereas, the present invention deals with the conversion of aromatics, olefins and naphthenes present in the feed into iso-paraffins. Based on the prior art details and drawbacks thereof, the present work is intend to provide a process for the reformulation of the FCC gasoline, where, most of the olefins and aromatics present in the feed have been converted into branched paraffins using a porosity modified, acidity modified zeolite supported noble metal based catalyst.